Medallion L4-2165cc 2.2L (1988)
Technical Service Bulletin # 085988
Date: 881212
Hella Cruise Control - Service
Models 1988 Medallion
Subject
Hella Cruise Control Service
Index ELECTRICAL
Date
December 12, 1988
No. 08-59-88 (C08-69)
P-5146
This bulletin provides service information for vehicles equipped with a Hella Cruise Control System. The Hella system was released as a running change
in 1988 on vehicles built after Fabrication No. U016355 for sedan and U005098 for station wagons. The Hella system is not interchangeable with the
Renix system used on earlier vehicles. No attempts should be made to retrofit the Hella system to vehicles equipped with Renix cruise control.
The system can be identified by lowering the cruise control module from the left kick panel and inspecting the module. The Hella module is clearly
identified.
This bulletin supercedes I.S. Note 5E (M.R. 289). Copies of I.S. Note 5E should be destroyed.
DESCRIPTION
The Hella system consists of the following three control groups:
^
Vacuum Control - consists of a vacuum pump, a venting safety solenoid and a diaphragm that controls the throttle linkage.
^
Electronic Control - consists of the electronic cruise control module and an engine overspeed relay.
^
Safety Control - consists of the master instrument panel control switch, switches on the steering wheel, and the brake and clutch switches.
Power
When the master instrument panel control switch is turned on, power is supplied to the engine overspeed relay and the cruise control module.
The overspeed relay then powers the cruise control module stop contact through the brake and clutch switches. It also powers the vacuum pump and the
safety solenoid.
NOTE:
THE GROUND PATH FOR THE SAFETY SOLENOID AND THE INSTRUMENT CLUSTER INDICATOR IS PROVIDED BY
THE CRUISE CONTROL MODULE ONLY WHEN THE VEHICLE IS MOVING FASTER THAN 48 KM/H (30 MPH), WHICH
THE MODULE DETERMINES AT THE SPEED SENSOR INPUT.
The steering wheel is equipped with two switches. One switch permits acceleration and memory storage of a vehicle speed as follows:
By pressing the "SET/ACCEL" button, the voltage from the control module (5 volts) passes through a resistance of 100 ohms. As long as the pressure is
applied, the vehicle accelerates. The speed is set when the button is released. The speed may also be set by pressing on the accelerator pedal and pressing
the "SET/ACCEL" button the moment the desired speed is obtained.
The information is translated by the cruise control module which keeps track of two parameters:
^
Real vehicle speed as determined by the speed sensor.
^
Memory storage of the desired speed.
Continuous comparison of these two speeds permits control of the vacuum pump causing a vacuum in the diaphragm assuring vehicle speed stability (the
pump has a regulation solenoid).
If regulation is interrupted (pressure on the brake or clutch pedal), press the Resume button on the steering wheel switch. The voltage from the control
module (5 volts) passes through a resistance of 330 ohms. The information is translated by the control module and the vehicle automatically returns to
the earlier speed stored in memory.
